made some tests with the the VCV Rack and Numerology4 using the Bridge AU plugin and a IAC Bus for sending MIDI and it works perfect. You just have to take care that you have to save the VCV Rack beside the Numerology project.
What needs more testing is how the latency behaves if you use the VCV and other stacks side by side.
The only problem I found is that the VCV Rack in the moment only allows one MIDI in module, but they are working on a fix.

There are two ways that I used Numerology & VCV Rack together to create this album. (This was with VCV Rack v.5.1. So before they had the awesome VCV Bridge that makes things a little easier to do now.)

1. Numerology MonoNote to IAC Bus to VCV Rack Midi-1. Then add a bunch of S&H LFOs to modulate the MonoNote. On VCV side, you now can use the MonoNote's midi output to control clock, gate, pitch and so on. You can also use multiple MonoNotes, just have to change the midi channels within the MonoNotes and have an individual Midi-1 in VCV Rack for each channel.

2. Route VCV Rack's audio output to Numerology through Soundflower which then let's you now use all your AU FXs to manipulate the audio even more. With a bunch of LFO modulations on AU FX parameters, you're able to add whole new dimensions to the VCV Rack sounds.

Hopefully all that made some sense. It's a pretty simple setup and hardly touches the possibilities of the combination of these two together. My next thing to try & tackle is the OSC routing from VCV Rack into Numerology.

Just tested VCV Rack & Numerology OSC capabilities and happy to say everything works as expected. TrowaSoft's cvOSCcv let's you send VCV Rack's cv over to Numerology super easy. Within Numerology, you can then use the "Learn OSC" function to control parameters.

One thing that you have to make sure though, when you setup Numerology's Generic OSC Controller, the OSC Port has to be the same as TrowaSoft's cvOSCcv Out Port. For my case, it was 7000.

Also to note, if you want to control a parameter of an AU Synth or FX, the trick I found was to "Add Modulation" to that parameter with a Sequencer. Then make the start and end point of the sequencer 1 & 1. "Learn OSC" on that first node and you're good to go. {After some thought, the Fader Box and ParamMod may be the best ticket to achieve this.}